This program is concerned with the effects of biological response modifiers on cancer and on the immune and hematopoietic system. We will pursue two principal approaches - the study of agents whose primary action does not involve a specific immune response to cancer antigens, and the investigation of modalities that utilize current knowledge of cancer-specific antigens and of immune reactions directed against them. Agents to be investigated in the first category include interferons, thymic fractions, bacterial lipopolysaccharide and other bacterial products. In the second category, we will investigate the serological response to vaccines containing serologically defined cancer cell surface antigens, the possibility of augmenting the response by manipulations aimed at reducing suppressor cell activity, and the use of monoclonal antibodies against cancer cell surface antigens in diagnosis and therapy. The clinical program depends on, and is backed up by, extensive laboratory investigation.